1. Field of the Invention
The present invention relates to a display panel with pixels, including current driven type light emitting elements, arranged in a matrix shape.
2. Description of the Related Art
Because an organic EL display that uses organic EL elements, being current driven light emitting elements, is of the self-emissive type, it has high contrast and fast response, making is suitable for moving picture applications such as a television for displaying natural images. Generally, an organic EL element is driven with a fixed current using a control element such as a transistor, but the transistor in that case is used in the saturation region. Therefore, even if the same gradation voltage is supplied, a different current is generated in each pixel due to variations in characteristics such as Vth (threshold voltage) and mobility of the transistors, making it difficult to maintain uniformity of emission brightness. In order to solve this problem, means having a circuit for compensating for Vth provided inside a pixel is disclosed in patent document 1.    Patent document 1: JP2002-514320T
If the Vth correction circuit shown in FIG. 3 of patent publication 1 is used, a gradation signal voltage is normally applied to the gate terminal of a drive transistor for supplying current to an organic EL element to offset that Vth. Vth of the drive transistor is therefore automatically corrected. However, it is also difficult to correct mobility of carriers such as electrons in the transistor with the Vth correction circuit of the related art disclosed in patent document 1, and it is difficult to ensure high brightness uniformity over a wide gradation range when there are variations in mobility between pixels.